The use of eDNA by as a robust, efficient, method to assess remote coastal islands for invasive terrestrial mammals
Abstract
Coastal islands, long known for their biodiversity amd unique ecology, face grave threats such as sea level rise, development, and biological invasions, among others. Despite this, basic knowledge of the prevalence of island dwelling species and their pressures is often lacking, and knowledge aquisition may be hindered by the logistics and costs of conducting offshore, or even nearshore, biological inventories. In light of the need for environmental practitioners to be able to survey islands quickly and efficiently, we test off-the-shelf commmerical environmental DNA water sampling equipment, universal primers, and commerical metabarcoding lab services, as tools to rapidy inventory coastal islands for mammalian biodiversity and invasive terrestrial threats. We collected enviromental DNA from sites (n = 35) on four coastal islands in Nova Scotia, from substrates including small turbid pools, dug wells, brackish coastal overwash, barachois ponds, and shallow emergent subsurface streams. Using a mammal-specific (MiMammal-U) metabarcoding markers, we detected the presence of invasive mammal species such as mouse (Mus musculus), rat (Rattus norvegicus), snowshoe hare (Lepus americanus), red squirrel (Tamiasciurus hudsonicus), could detected also conversely discharge after a haveay rainfall investigation is needed to upscale this promising approach as a powerful tool to monitor catch composition, assess the distribution of stocks, and generally record hanges in fish communities across the oceans coastal islands thaintroduced invasive species are present on all islandscan be used as an efficent tool to on the collected eDNA inventoried invasise nvase terestrail mammlas on all islands, species on all Our results sugegsrtion invebntory and monitoring an integra;l compenten necessary for efficet mangemten. Condition assseessemnt exotic species have expanded, and native species have gone extinct We investigate the use of environmental DNA obtained from water as a tool to assess the occurrence of non-native and problematic terrestrial mammals on remote coastal islands in Atlantic Canada.
Use of environmental DNA to detect the present of terrestrial or semi-aquatic organisms is now well established (Ficetola, Miaud, Pompanon, & Taberlet, 2008; Harper et al., 2019; Leempoel, Hebert, & Hadly, 2020; Lyet et al., 2021; Neice & McRae, 2021; Saenz-Agudelo et al., 2022; Sales et al., 2020)
how robust the technology can be
Depending on the system and species, various studies have documented a positive correlation between the eDNA concentration measured and target species abundance or biomass
as a way We sampled environmental DNA, extracted from water, to assess terrestrial mammalian threats and biodiversity on coastal islands situated in a logistically challenging, ecologcially threatened, maritime landscape.s, We test the use of environmental DNA as a tool to provide such assessments, from the prespective of non-expert environmental practitioners in need of system that combines ease-of-use, robustness, and quality assurance. Our study sites fall within an archipelago in the province of Nova Scotia, Canada, which consists of some 4000 islands and skerries, many of which are threatened by rising sea levels, biological invasions, and human developement. As conservation organizations and governments move to prioritize and secure new island landholdings, there is increased need for rapid, cost-efficent assessment of island biodiversity and threats. To assess the diversity of native, problmatic native, and invasive terrestrial mammals on island To implement science-based conservation management and decision-making, a necessary first step is the detailed, on-the-ground assessment of species and their threats. Such lansdcapes have long relies on de facto conservation, due to remotmessn, and boost legal protection of exisiting island holdings, We investigate the use of environmental DNA obtained from water samples as a tool to assess diversity of terrestrial native, non-native, and problematic species,on remote coastal islands in Atlantic Canada.We investigate the use of environmental DNA obtained from water samples as a tool to assess diversity of terrestrial native, non-native, and probklematic species,on remote coastal islands in Atlantic Canada.
Alternative, direct methods include infrared cameras, hair tunnels, cage and snap trapping, some of which require intensive training, frequency checking, and extra levels of approvals and permitiing.
Coastal islands, globally, are threatened by changing climate, nonnative invasive or other problematic species, habitat degradation, among others. he lack of data and evidence that was underpinning environmental management
The purpose of this work is to continue the survey effort of breeding birds and their threats on coastal islands in Nova Scotia, and to catalyze effective action for conservation in a threatened region of high biological diversity and ecological uniqueness. The study site falls within one of Nova Scotia’s most diverse regions, and conservation actions in the area are an ongoing priority for the Canadian Wildlife Service, the Nova Scotia Department of Natural Resources and Renewables, and the Nova Scotia Nature Trust, among others. As conservation actions are largely based on fine-scale knowledge about species distributions and their threats, we aim to: A) conduct holistic inventories of birds and problematic mammal species in a key conservation area that has not been recently evaluated, and B) find ways to improve monitoring of wildlife and their threats by deploying new detection methods for invasive and problematic species through use of camera traps, acoustic sensors and eDNA. Our studies will help assess the ecological value of the region, and inform decision makers involved in the transfer of lands for inclusion within the protected areas network known as the Atlantic Canada Archipelago. Further, knowledge generated from our work will help identify and develop threat mitigation strategies and inform any future whole island restoration efforts.
Field sites and collection of samples